I have 2 computers (home PC's). Both are connected to the internet through a router/switch.
The router is always powered, regardless when one (or both PC's) are going standby.
Idea is, to power the router from the PC power supply (by homemade cable ofc.), so When PC goes standby the 12 Volt are shut off and so the router (note also that this avoids the router power adapter).
The trick is to have this happen from both two PC's – aka power on/off the router by a common connection from both. If both (or only one powered) are off/on the router follows, and we save the world energy.
I already have made such a connection – and it work fine. But I'm still concerned by any power/voltage imbalance between the two PC's.
Below is how I made the wiring with 2 protection diodes.
But still i think that one PSW could feed into the other. I also considered a relay which could isolate 100%, but this would give a short delay in power when shifting.
Are there any other wiring (or device/chip) to solve this perfectly.
Tx for any answers
Best Answer
Why do you "think that one PSW could feed into the other"? ORing diodes is pretty much a standard solution to prevent this, recommended by PSU makers, e.g. http://www.kepcopower.com/support/diodes.htm. As long as the diodes are properly selected so they don't overheat, I don't see an issue here. You could use Schottky diodes to reduce the voltage drop seen by the router and simultaneously decrease power dissipation on themselves, but since you said it already works with the diodes you've tried... it seem a bit pointless to bother now.
The mismatched voltages are a problem when you want to load-balance the sources on a load (e.g. see http://www.codemsys.com/smps/Parallel.htm), but that issue seems irrelevant to your application as either PC source can presumably power its PC and the router (presumably a home model) comfortably.
There are slightly more expensive stock IC solutions for redundant power supplies, which is basically what you're doing from the router's perspective, (e.g. see http://www.ti.com/lit/an/slva094/slva094.pdf), which have some additional advantages like almost zero voltage drop to the load, but they seem overkill for your application.